Value document

ABSTRACT

The invention relates to a document of value such as a paper of value or ID card with a security element having an optically variable material. Said optically variable material conveys different color effects at different viewing angles. Additionally, the security element has at least one machine-readable feature substance that does not impair the visually visible optically variable effect of the optically variable material.

BACKGROUND

This invention relates to a document of value such as a paper of valueor ID card with a security element having an optically variable materialthat conveys different color effects at different viewing angles. Theinvention further relates to a foil, a multilayer transfer material anda printing ink with such an optically variable material.

In view of the high quality of color copies it is necessary to providedocuments of value such as bank notes, ID cards or the like withadditional security elements that are uncopiable or not copiable true tothe original. For this purpose one frequently uses optically variabledevices such as holograms, interference layer elements or liquid-crystalmaterials that convey different color effects at different viewingangles. The interplay of colors of said devices constitutes a verystriking, visually easily recognized security feature so that aphotocopy not having said interplay of colors can be distinguished froman original document very easily even by a layman. However, opticallyvariable devices are accessible to machine testing only under certainconditions and with high technical effort.

EP 0 435 029 B1 describes a document of value with an opticallyvariable, liquid-crystal security feature. One uses as security elementsin particular liquid-crystal polymers that constitute a plastic-likesolid with a distinctive color change at room temperature after suitablyoriented production. They can be used to produce different types ofsecurity elements. One can thus coat plastic foils with a layer ofliquid-crystal polymers and then cut the resultant sheet of materialinto narrow bands or threads that can be embedded in paper or othermaterials as security threads. It is also proposed in EP 0 435 029 B1 toproduce transfer bands containing in their layer structure a layer ofliquid-crystal polymers. Besides optically variable properties,liquid-crystal materials also possess light-polarizing properties thatare exploited to make the security element additionally accessible tomachine testing. Since light polarization is only a weak effect that isgreatly impaired by environmental influences such as dirt, folds orbends in the document of value, however, the measuring effort forreliable automated testing is very high.

SUMMARY

The invention is therefore based on the problem of proposing a documentof value with an optically variable security element having not only avisually well recognized optically variable effect but also improvedmachine-readability.

The invention is based on the surprisingly simple idea of not improvingthe machine-readability of the optically variable material itself butcombining the optically variable material with at least one featuresubstance that is easily and reliably machine-readable while notimpairing the visually visible, optically variable effect of theoptically variable material. Accordingly, the inventive security elementhas an optically variable material that conveys different color effectsat different viewing angles, and a feature substance that does notimpair the visually visible, optically variable effect of the opticallyvariable material and is machine-testable. The security element can beprepared as a separate element and then connected with the object ofvalue to be protected, or produced directly on the object of value, forexample in the form of a printed image.

As a feature substance one can use for example luminescent substances,electrically conductive polymers or carbon blacks, IR-absorbentsubstances, but also magnetic materials or thermochromic materials.Preferably, one uses feature substances transparent in the visiblespectral region.

In the case of luminescent substances, suitable ones are specificallysubstances luminescing outside the visible spectral region with narrowemission bands that are very well detectable by machine. One preferablyuses inorganic luminescent substances, but depending on the applicationit may also be expedient to use other luminescent substances.

Magnetic materials frequently possess a black or dark inherent color. Ifthe quantity concentration is accordingly dosed, however, they cannevertheless be used very advantageously as a feature substance inaccordance with the invention. The dark magnetic materials absorb thediffuse stray radiation in the surroundings of the optically variablematerial, thereby strengthening the brilliance of the optically variableeffect.

As an optically variable material one can use for example liquid-crystalmaterials, preferably liquid-crystal polymer materials or alsointerference layer materials. It has proved especially advantageous ifthe optically variable material is present in the form of pigments orparticles with a suitable particle size, distribution and shape factorsince the latter can be admixed to any other materials. One can choosebetween pigments with body color and ones without body color. The latterare largely transparent so that their color effect is greatlycodetermined by the background. But one can also use microencapsulatedliquid crystals.

According to a preferred embodiment, the security element consists of acolor layer applied at least in partial areas of the document of value.The color layer consists at least of a binder and liquid-crystalpigments dispersed therein as well as feature substances. If the colorlayer is applied by a printing process, for example screen printing,flexography or intaglio printing, the printing ink contains opticallyvariable pigments in 10 to 30 wt % and feature substance in 0.01 to 30wt % based on the binder, depending on the feature substance used. Ifthe feature substance used is a luminescent substance, one adds 0.01 to30 wt %, preferably 0.01 to 10 wt %, in the case of magnetic materials 5to 80 wt %, preferably 10 to 20 wt %. If electrically conductivepolymers are used for the feature substance, the electrically conductivepolymer can also form the binder of the color layer.

Alternatively, the security element can also be present in the form of athread or band that is either disposed completely on the surface of thedocument of value or freely accessible only partially on the surface ofthe document of value as a so-called window security thread. Thesecurity element in this case has a plastic material containing forexample the optically variable material and feature substance.Alternatively, one can apply a color layer containing the opticallyvariable material and feature substance to the plastic material at leastin certain areas. According to another variant, the security element hasan electrically conductive plastic material on or in which the opticallyvariable material is disposed.

According to another embodiment of the invention, the security elementcan also consist of a plastic foil containing the optically variablematerial and feature substance. Said plastic foil can be used forexample as a protective layer for certain areas of the document of valueor as an all-over cover foil, for example in the case of ID cards.

It is likewise possible to add the optically variable material andfeature substance to plastic pellets that are then processed intofinished plastic parts. This can be done for example by extrusion orinjection molding.

Finally, it is also possible to form the security element as amultilayer transfer element in whose layer structure the opticallyvariable material and feature substance are disposed. The transferelement can be executed as a self-supporting label consisting of acarrier layer on or in which the optically variable layer and featuresubstance are disposed. Alternatively, the transfer element can have nocarrier layer. In this case the transfer element is produced with theaid of a hot stamping foil whose carrier band is removed after transferof the transfer element, i.e. the security element.

Feature substance and optically variable material need not fundamentallybe applied simultaneously to the object of value, however. One can forexample first apply the feature substance and then dispose the opticallyvariable material there-over. This procedure is especially advantageousif the feature substance used is dark magnetic material or electricallyconductive carbon black and the optically variable material is largelytransparent material without, or with little, body color. In this casethe feature substance is first applied in the form of a printed imageand then in the same area a layer of optically variable material thatmay also cover gaps present in the printed image of the featuresubstance. Since the dark background absorbs the radiation passingthrough the optically variable material as well as stray radiation, theoptically variable effect is especially evident in the area of themagnetic printed image.

The forgery-proofness of this security element can be additionallyincreased if a magnetic material is used as the feature substance andcarbon black is admixed to the magnetic layer. Concentrations of 1 to 5wt % of carbon black already yield good electric conductivity that isreadily detectable by machine.

Another way of additionally increasing forgery-proofness is to apply thefeature substance in the form of a coding or alphanumeric information.In the simplest case, the coding is a bar code. If the coding is not tobe visually visible, the surroundings of the coding can be provided inregister with a camouflage layer that cannot be distinguished visuallyfrom the coding but contains no feature substance. Such camouflaging mayalso be expedient if the layer containing feature substance istransparent since the layer might be recognizable at a glancing angle.

During machine testing of the security element, several differentproperties can be evaluated. Most optically variable materials, inparticular liquid-crystal materials, are transparent in the IR spectralregion. If said materials are combined with a luminescent substancetransparent in the visible spectral region and emitting in the IRspectral region, the spectral response in the visible and infrared waveranges can be evaluated to detect the optically variable material duringmachine testing. Simultaneously, one must test at the same place thespecial physical property, for example luminescence or electricconductivity of the feature substance.

If the feature substance is not transparent, one can nevertheless applythe same measuring principle. In this case one uses as a reference valuethe superposition of the spectra of optically variable material andfeature substance in the visible spectral region.

The optically variable material can finally also be combined withthermochromic materials whose color change can be detected with asuitable optical sensor. As thermochromic materials one can use forexample suitable liquid-crystal materials that show a defined colorchange and have short reaction times.

The forgery-proofness of the inventive security element can finally beincreased further by using a plurality of optically variable materialsand/or feature substances that may be disposed in the same or differentlayers of the security element.

If a liquid-crystal material is used as an optically variable material,additional information can also be incorporated in this layer. Liquidcrystals have the property of dispersing unpolarized incident light intocomponents with different polarization. Depending on the chemicalcomposition of the liquid-crystal material, only one of these componentsis reflected. This property can be used according to the invention forrepresenting information. For example, one can produce any desiredinformation with a printing ink containing left-handed liquid-crystalmaterial. The surroundings of this information is printed in registerwith an ink containing right-handed liquid-crystal material. Both inksshow the same appearance under normal illumination so that theinformation cannot be recognized under normal illumination conditions.The information only becomes recognizable when viewed through a suitablepolarization filter since the radiation passing through the polarizationfilter is reflected only by one of the liquid-crystal materials so thata brightness contrast arises between the two printed layers.

One or both of the liquid-crystal materials can additionally havethermochromic properties so that suitable heating of said material, forexample by the body heat of a finger, produces a color change that istestable by machine and/or visually.

If both liquid-crystal materials have thermochromic properties oneobtains further interesting variants. For example the materials can bechosen so that they show a color change at the same temperature but theperceptible colors are different. In this way one can likewise representinformation that becomes recognizable, disappears or alters its contentthrough heating. One preferably uses materials that look the same undernormal conditions and show different colors in contrast with each otherthrough heating. It is also possible to use materials that becometransparent or opaque through heating.

The additional thermochromic property can be incorporated directly viathe chemical formulation of the liquid-crystal materials. For optimalcontrol of the individual properties, however, it is also recommendableto mix a plurality of liquid-crystal materials, each of theliquid-crystal materials having a special property. That is, one canselect for example two basic liquid-crystal components that have right-or left-handed properties and matching reflective behavior but are notthermochromic. These are mixed with corresponding thermochromicliquid-crystal materials.

The inventive security element can moreover be used not only forprotecting documents of value such as bank notes, ID cards, passports,shares or the like, but can also be disposed on or in any desiredobjects to be protected, for example tickets, books, CDs, packages ofany kind, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and embodiments of the invention will be explainedwith reference to the figures, in which:

FIG. 1 shows an inventive document of value,

FIG. 2 shows an embodiment of the inventive security element,

FIG. 3 shows another embodiment of the inventive security element,

FIG. 4 shows another embodiment of the inventive security element,

FIG. 5 shows another embodiment of the inventive security element,

FIG. 6 shows another embodiment of the inventive security element,

FIG. 7 shows another embodiment of the inventive security element,

FIG. 8 shows another embodiment of the inventive security element,

FIG. 9 shows another embodiment of the inventive security element in afront view,

FIG. 10 shows a special embodiment of an inventive liquid-crystal layerwith right- and left-handed polarization properties.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

FIG. 1 shows inventive security document 1 in the form of a bank note.So-called window security thread 2 is woven into said bank note, passingdirectly to the surface of the paper in certain areas 3. The areas ofthread 2 located therebetween within the paper web are shown by dashlines in the figure. Document of value 1 additionally has print 4produced with an inventive printing ink. Print 4 forms the inventivesecurity element. Since one does not normally produce the entire printof the document of value with the inventive printing ink, this is alocally limited security element, as indicated by area 5 limited bydash-dotted lines in FIG. 1. If necessary, however, the entire print canbe done with the inventive ink.

The inventive printing ink contains an optically variable material, forexample liquid-crystal pigments or interference layer pigments, as wellas at least one machine-readable feature substance. The opticallyvariable pigments can have a body color if the print is to be ratheropaque. In case information or color layers located therebelow are toremain visible, one uses translucent optically variable materialswithout body color.

The machine-readable feature substance may be luminescent substancestransparent in the visible spectral region. Transparent featuresubstances offer the advantage of not impairing the visual color effectof the optically variable material and not appearing visually otherwisein any way. Since forgers generally confine themselves to imitating thevisual impression of an object of value, these forgeries can bediscovered very easily by checking the machine-detectable property ofthe feature substance.

It is also possible to use magnetic pigments, in particular blackmagnetic pigments. The concentration of magnetic pigments must, however,be chosen so that the visual impression of the optically variablepigments is not impaired. If the magnetic pigments are added in lowconcentrations, they even support the optical effect of the opticallyvariable pigments since they absorb the diffuse stray radiation.

FIG. 2 shows another embodiment of the inventive security element. Inthis case it is security thread 20 that, as already shown in FIG. 1, canbe embedded in the bank note as a window security thread. It consists ofcarrier material 6 that can be transparent plastic material. Disposed onsaid carrier material is optically variable layer 7 containing featuresubstance 8. Optically variable layer 7 may be executed as a printedlayer or likewise as a foil layer. In the case of a color layer, featuresubstance 8 can constitute the binder for example.

FIG. 3 shows another embodiment of inventive security element 21. Inthis case it is self-supporting foil 9 that has both the opticallyvariable effect and feature substance 8. Said foil can be applied in theform of labels for product protection to any kind of object to beprotected. It can alternatively also serve as a cover foil, for examplefor passports or ID cards. Foil 9 can also be cut into bands or threadsof a certain width, however, that are fastened to a document of value orproduct, or embedded in a paper of value as a window thread.

FIG. 4 shows inventive transfer material 22 in whose layer structure theoptically variable material and feature substance are disposed. Itconsists of carrier foil 10 that can be provided with separation layer11 in order to permit the layer structure to be detached from thecarrier band. Layer 12 can be formed as a foil layer or also as aprinted layer and contains both feature substance 8 and the opticallyvariable material. On layer 12 one may finally dispose adhesive layer13, preferably a hot-melt adhesive layer. The layer sequence of transfermaterial 22 can of course be supplemented by additional layers dependingon the application. If layer 12 is a printed layer, for example, it maybe expedient to dispose another protective layer between separationlayer 11 and layer 12 in order to protect the security element fromharmful environmental influences after transfer to the document ofvalue.

A feature substance can likewise be incorporated into said protectivelayer. Another alternative provides for incorporating the featuresubstance only in said protective layer so that layer 12 contains onlythe optically variable material.

Said transfer material 22 is then contacted with the document of valueto be protected and subjected to pressure and/or heat in the areas to betransferred so that the layer structure located on carrier material 10bonds firmly with the document material and remains on the document whencarrier material 10 is then removed.

Transfer material 22 can also be used analogously to above-describedself-supporting foil 9 for protecting any other desired objects.

FIG. 5 shows document of value 14 with another embodiment of inventivesecurity element 23 in cross section. Document of value 14 bearsdark-colored print 16 containing feature substance. Printed image 16 canrepresent for example a coding or alphanumeric information. Disposedthereover in a large-surface area is optically variable material 15having no or little body color. This may be for example liquid-crystalpolymer material or also interference layer material, as sold under thetrade name IRIODINE® by Merck. It is preferably admixed in the form ofpigments to a printing ink or brushing paint that is applied to thedocument. The visual effect of optically variable material 15 stands outclearly in the area of dark printed image 16 while it is only veryweakly recognized in the remaining areas due to the transparency of theoptically variable material and the diffuse stray radiation that occurs.

Dark printed image 16 can be produced by means of a printing inkcontaining magnetic pigment, or a printing ink with another featuresubstance admixed thereto. This may be for example a blackIR-transparent ink with one or more luminescent substances emitting inthe IR spectral region admixed thereto. Alternatively, one can use aprinting ink containing carbon black and having an electric conductivityeasily tested by machine.

Additional protection can be obtained if printed image 16 consists of amachine-detectable printing ink only in certain areas. That is, parts ofentire printed image 16 are printed with a dark ink containing neithermagnetic pigment nor luminescent substance and the remaining parts areproduced with the ink containing feature substance. This permits notonly the existence of the feature substance to be detected in the areaof the optically variable material during machine testing, butadditionally its distribution evaluated.

The ink used for producing printed image 16 can of course also contain aplurality of feature substances, for example a mixture of magneticpigments and luminescent substances. It is also possible to use aplurality of optically variable materials.

This embodiment according to FIG. 5 is especially advantageous ifhigh-resolution images are to be produced with the aid of opticallyvariable printing inks. Due to the necessary pigment size and theplatelike shape of most optically variable materials, the latter cannotbe printed in the form of fine, high-resolution patterns, for exampleguilloches with a line thickness smaller than 0.1 mm as a positive ornegative printed image. They are therefore usually applied by screenprinting. Fine line thicknesses of less than 0.1 mm, on the other hand,can usually be obtained only by offset, indirect letterpress or similarprocesses. The feature substances can now be processed with theseprinting processes so that inks with feature substances can be printedwith high resolution. This has the consequence that the visual effect ofthe optically variable material nevertheless appears as ahigh-resolution pattern in the finished security element due to the darkbackground.

Alternatively, the high-resolution pattern can be printed with aconventional dark to black ink that is supplemented by an adjoiningpattern containing feature substance. The layer containing featuresubstance is preferably transparent in this case.

FIG. 6 shows document of value 14 on which another embodiment ofinventive security element 24 is disposed. Security element 24 consistsof magnetic layer 32 containing carbon black components 17. Disposed onsaid layer is translucent optically variable layer 15 additionallycontaining luminescent substance 18. Luminescent substance 18 may be forexample a luminescent substance transparent in the visible spectralregion and emitting in the visible spectral region under UVillumination.

This easily produced security element has several properties testable bymachine and visually. One can thus use for visual testing both theoptically variable material and the emission of the luminescentsubstance excitable by UV light. For machine evaluation one can detectthe magnetic properties and the luminescence emission under UVillumination. Additionally, one can evaluate the electric conductivityproduced by the carbon black admixture.

FIG. 7 shows a similar embodiment of inventive security element 25.Here, too, magnetic layer 32 with admixed carbon black is first appliedto document of value 14. On said layer one then provides layer 19containing a luminescent substance emitting in the IR spectral region.Finally, one disposes thereover optically variable layer 15 transparentin the IR spectral region.

The layers shown in FIGS. 6 and 7 do not have to be disposed congruentlyover each other, as shown in the figures. The magnetic layer can thus beapplied in the form of a printed image, similarly to FIG. 5. The sameapplies to luminescent layer 19. The layers containing featuresubstances can also be disposed side by side, preferably directlyadjacent to each other.

FIG. 8 shows another embodiment of inventive security element 26 whereinthe feature substance is applied in the form of a coding. In the exampleshown, a layer containing feature substance is provided on document 14in the form of a bar code that consists of spaced-apart areas 30.Intermediate areas 31 are filled with a layer containing no featuresubstance but visually showing the same appearance as areas 30. Overlayers 30, 31 one disposes optically variable layer 15.

Such an embodiment is especially advantageous if the optically variablematerial is a quasi transparent interference-layer or liquid-crystalmaterial whose color effect is strongly accentuated by a darkbackground. In this case the color effect of layer 15 is accentuated inthe entire area of dark to black areas 30, 31 but not the entire areahas feature substance. The feature substance used may be for example anIR-absorbent substance. Said substance may simultaneously be magnetic.Areas 31 are in this case preferably printed with an IR-transparentlayer.

According to another embodiment, only areas 30 may be provided, i.e.areas 31 with a camouflaging effect in the visible spectral region maybe omitted.

FIG. 9 shows a front view of a special embodiment of the inventivesecurity element that combines the teachings and embodiments explainedwith reference to FIGS. 5 and 8. Said security element 27 consists of acolored, preferably dark or black, print having in certain areas gaps 38in the form of patterns or alphanumeric characters. In the area of print36 there is additionally bar code 37 showing the same appearance undernormal illumination conditions as print 36 so that bar code 37 is not tobe recognized visually. In FIG. 9 bar code 37 has been accentuated inclearly recognizable fashion for reasons of clearness, however. Unlikeprint 36, the ink with which bar code 37 was produced contains amachine-detectable feature substance, preferably an IR-absorbentsubstance. The printed image composed of components 36, 37, 38 iscovered all over by translucent layer 39, preferably a liquid-crystallayer. As explained above, the optically variable effect of layer 39stands out clearly primarily in the area of prints 36, 37.

Security element 27 can be produced in different ways. Thus, prints 36,37 can be printed in register side by side. That is, if print 36 isproduced in the first printing cycle, the areas of bar codes 37 alsoremain unprinted in said printing cycle and form gaps in print 36. Inthe second printing cycle, bar code 37 is supplemented with inkcontaining feature substance. Alternatively, prints 36, 37 can bedisposed one over the other. It must thereby be heeded that the ink ofprint 36 must not impair the machine-readability of bar code 37.

According to another variant, both print 36 and print 37 can contain afeature substance, the feature substances differing with respect to aphysical property. One preferably uses IR-absorbent substances whoseabsorption peaks are in different spectral regions.

The security element can be designed more elaborately and thus also withhigher forgery-proofness if the optically variable layer is composed ofa plurality of optically variable materials with different physicalproperties. A special embodiment of such an optically variable layer isshown in FIG. 10. FIG. 10 only shows a front view of optically variablelayer 39 shown in FIG. 9. In this case, optically variable layer 39 iscomposed of two materials with different properties. One of theoptically variable materials is disposed in area 40 and the other inarea 41. Area 41 has the form of alphanumeric characters in the exampleshown. Areas 40, 41 can also have any other contour form, however.

One preferably produces areas 40, 41 using for liquid-crystal materialswith different light-polarizing properties. Depending on the chemicalcomposition of the liquid-crystal material, only light with a certainpolarization is reflected. The chemical composition can be chosen sothat two liquid-crystal materials look the same visually but reflectdifferently polarized light.

If areas 40, 41 shown in FIG. 10 are covered with such liquid-crystalmaterials the information represented by areas 41 cannot be recognizedunder normal viewing conditions. The information becomes recognizableonly when layer 39 is viewed through a polarization filter passing onlylight of one polarization direction.

According to another embodiment, the liquid-crystal materials disposedin areas 40, 41 can additionally be provided with a feature substance,for example a luminescent substance. Both liquid-crystal materials canbe provided with the same or different feature substances, such as twodifferent luminescent or thermochromic substances. A luminescent and athermochromic substance are also possible since the feature substancesdo not need to have the same testable property. If the security elementis to have thermochromic properties, the liquid-crystal materials canalso be chosen so as to have both different polarization properties anddifferent thermochromic properties.

One can thus use for area 40 a liquid-crystal material havingleft-handed properties and showing a color change when subjected to bodyheat. At the same time the material is provided with a first luminescentsubstance transparent in the visible spectral region. Area 41, however,is covered with a right-handed liquid-crystal material that likewiseshows a color change when subjected to body heat, but contrasts in colorwith that of the liquid-crystal material in area 40. Said secondliquid-crystal material is also provided with a second luminescentsubstance transparent in the visible spectral region. The emissionwavelengths of the two luminescent substances differ, however. Thispermits the information represented by areas 40, 41 and not recognizableunder normal viewing conditions to be made visible or detected with theaid of polarization filters via the polarizing properties of theliquid-crystal materials, by heating via the thermochromic properties ofthe liquid crystals or by excitation of the emission of the luminescentsubstances.

This way of designing the optically variable layer explained withreference to FIG. 10 can of course also be used in all other embodimentsexplained.

It is likewise possible to provide the printed layer sequences shown inFIGS. 5, 6, 7, 8 and 9 on a security thread or in a transfer material.The transfer material can be formed either as a hot stamping foil or aslabel material.

1. A document of value comprising a security element having at least oneoptically variable material that conveys different color effects atdifferent viewing angles, and at least one machine-readable featuresubstance that does not impair a visually visible optically variableeffect of the optically variable material, the optically variablematerial and the feature substance being disposed in one layer and saidlayer being present in the form of information; wherein the opticallyvariable material is an interference layer material.
 2. A document ofvalue comprising a security element having at least one opticallyvariable material that conveys different color effects at differentviewing angles, and at least one machine-readable feature substance thatdoes not impair a visually visible optically variable effect of theoptically variable material, the optically variable material and thefeature substance being disposed in one layer and said layer beingpresent in the form of information; wherein the machine-readable featuresubstance is a material luminescing including a substance that isluminescent outside a visible spectral region.
 3. A document of valuecomprising a security element having at least one optically variablematerial that conveys different color effects at different viewingangles, and at least one machine-readable feature substance that doesnot impair a visually visible optically variable effect of the opticallyvariable material, the optically variable material and the featuresubstance being disposed in one layer and said layer being present inthe form of information; wherein the security element is present on thedocument of value as a multilayer transfer element in whose layerstructure the optically variable material and feature substance aredisposed.
 4. A document of value comprising a security element having atleast one optically variable material that conveys different coloreffects at different viewing angles, and at least one machine-readablefeature substance that does not impair a visually visible opticallyvariable effect of the optically variable material, the opticallyvariable material and the feature substance being disposed in one layerand said layer being a self-supporting plastic foil; wherein theoptically variable material is an interference layer material.
 5. Adocument of value comprising a security element having at least oneoptically variable material that conveys different color effects atdifferent viewing angles, and at least one machine-readable featuresubstance that does not impair a visually visible optically variableeffect of the optically variable material, the optically variablematerial and the feature substance being disposed in one layer and saidlayer being a self-supporting plastic foil; wherein the machine-readablefeature substance is a material luminescing including a substance thatis luminescent outside a visible spectral region.
 6. A document of valuecomprising a security element having at least one optically variablematerial that conveys different color effects at different viewingangles, and at least one machine-readable feature substance that doesnot impair a visually visible optically variable effect of the opticallyvariable material, the optically variable material and the featuresubstance being disposed in one layer and said layer being aself-supporting plastic foil; wherein the security element is present onthe document of value as a multilayer transfer element in whose layerstructure the optically variable material and feature substance aredisposed.